This invention relates to a reflection type screen for a projector on which images projected by a projector such as an OHP, slide projector, and film projector are displayed as reflected light. In particular, it relates to a reflection type screen for a projector suitable for projection of static images such as personal computer (abbreviated as PC, hereinafter) images etc.
Polarizing screens utilizing polarizing films or glass bead screens having retroreflection ability are used as high luminance screens capable of producing high contrast images even in a light room. However, polarizing screens and glass bead screens are problematic because of high cost, many manufacturing processes or difficulty in manufacturing, and narrow view angle. As a high luminance reflective screen with a wide view angle, a reflective screen provided with a reflective layer including aluminum paste or a pearl pigment has been proposed (Japanese Unexamined Patent Application Publication No.3-119334 (1991)).
In recent years, however, marked increases in the amount of light produced by liquid crystal projectors has made it possible to obtain high-contrast images in a light room without using a high luminance screen. Consequently, wider view angle has become more desired than luminance in the performance of the reflection type screen.
For improving view angle, there have been proposed projector screens with a reflective layer containing brilliant pigments such as aluminum pigments or a pearl pigment added with light diffusive agents such as mica powder or silicon oxide powder and thixotropic agents for preventing sedimentation of the brilliant pigments (Japanese Patent Unexamined Application Publication No.8-231904(1996)), and reflective screens having a reflective layer of aluminum paste in which resin beads of a specific refraction index are dispersed (Japanese Patent Unexamined Application Publication No.6-148746(1994)).
FIG. 2 shows a projector 20 which projects images displayed on a liquid crystal display of a PC 30 directly onto a reflective screen 10. Projectors of this type have come into common use in recent years. Generally, the characters of the PC image are displayed as dark parts against a bright main part (white field) of the PC image. Therefore, reflective screens for projecting such images are required to be capable of displaying the dark portions clearly and making bright part look xe2x80x9cwhitexe2x80x9d.
However, since the projector 20 generally uses a metal halide lamp as a light source, when conventional screens are used, color reproducibility is bad, that is, the bright part becomes yellowish or light orange due to its low color temperature or the entire screen looks gray.
Therefore, an object of the present invention is to provide a reflection type screen capable of projecting clear static images such as PC images and having a wide view angle. In particular, the present invention aims at providing a reflection type screen excellent in color reproducibility of the bright part of static images.
The reflection type screen of the present invention comprises a substrate having a light reflecting property and a light diffusion layer formed thereon, wherein the light diffusion layer contains a pearl pigment and a light diffusion agent dispersed in a binder resin and the pearl pigment has an optical property of reflecting blue light and transmitting light of a color complementary to blue.
The content of the pearl pigments in the light diffusion layer is preferably in the range of 5-100 parts by weight, more preferably in the range of 10-50 parts by weight based on 100 parts by weight of the binder resin. The content of the pearl pigment is preferably in the range of 10-150 parts by weight, more preferably 30-110 parts by weight based on 100 parts by weight of the light diffusion agent. The content of the light diffusion agent is preferably in the range of 10-100 parts by weight, more preferably 20-50 parts by weight based on 100 parts by weight of the binder resin.
Of the light emitted by the light source, the pearl pigment dispersed in the light diffusion layer of this reflection type screen transmits only light having a wavelength of about 570-610 nm, and reflects other light (blue light). Part of the transmitted light is reflected at the surface of the substrate. As a result, yellowish color is suppressed in the bright part of images and this part looks white as a whole. Therefore, PC images having many white parts can be exhibited clearly. In addition, luminance is not degraded since light absorption of the screen is small. In particular, when the contents of the light diffusion agent and the pearl pigment are in appropriate ranges, a reflective screen having a wide view angle and a high screen gain (SG) value can be obtained.